EP0307982B1 - Gerät zur Wiedergabe eines optisch lesbaren Aufzeichnungsträgers - Google Patents

Gerät zur Wiedergabe eines optisch lesbaren Aufzeichnungsträgers Download PDF

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Publication number
EP0307982B1
EP0307982B1 EP88201730A EP88201730A EP0307982B1 EP 0307982 B1 EP0307982 B1 EP 0307982B1 EP 88201730 A EP88201730 A EP 88201730A EP 88201730 A EP88201730 A EP 88201730A EP 0307982 B1 EP0307982 B1 EP 0307982B1
Authority
EP
European Patent Office
Prior art keywords
tracks
address
scanning spot
track
disc
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP88201730A
Other languages
English (en)
French (fr)
Other versions
EP0307982A1 (de
Inventor
Meine Jochum Peter Van Der Meulen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Koninklijke Philips NV
Original Assignee
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Philips Gloeilampenfabrieken NV, Koninklijke Philips Electronics NV filed Critical Philips Gloeilampenfabrieken NV
Publication of EP0307982A1 publication Critical patent/EP0307982A1/de
Application granted granted Critical
Publication of EP0307982B1 publication Critical patent/EP0307982B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
    • G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel
    • G11B27/102—Programmed access in sequence to addressed parts of tracks of operating record carriers
    • G11B27/105—Programmed access in sequence to addressed parts of tracks of operating record carriers of operating discs
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
    • G11B7/005—Reproducing
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/085—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam into, or out of, its operative position or across tracks, otherwise than during the transducing operation, e.g. for adjustment or preliminary positioning or track change or selection
    • G11B7/08505—Methods for track change, selection or preliminary positioning by moving the head

Definitions

  • the invention relates to an apparatus for reproducing information recorded with a given write velocity and a given track pitch in substantial concentrical tracks on an optical readable record carrier, the information comprising an address code extending continuously along the track and indicating the absolute time from the beginning of the tracks, so that a predetermined relation exists between the address code and number of tracks, counted in radial direction, said relation having parameters which depend on the write velocity and track pitch, said apparatus comprising
  • Such an apparatus will be an apparatus for optically reading records on which information provided with addresses is recorded in a spiral track or in a plurality of concentrical tracks.
  • Such an apparatus may be particularly a Compact Disc Digital Audio disc player or briefly CD player for playing digital audio discs or a Compact Disc Read Only Memory player or briefly CD-ROM plays for playing digital data discs.
  • sub-code information is also recorded on a digital audio disc, which sub-code information comprises, inter alia an absolute time code expressed in minutes, seconds and frames (1/75 s) which indicates the time elapsed from the start of playing the disc.
  • This time code is used as an address code in order to bring the scanning spot of the light beam to a desired radial position on the disc.
  • this address code is exclusively used for finding the beginning of the music tracks on the disc.
  • the absolute time codes of the beginning of the music tracks present on the record expressed in minutes and seconds, are indicated on the lead-in track of an audio disc. Since seconds are not sufficiently accurate to find the beginning of a music track, use is made of the relative time code which is also incorporated in the sub-code signal and which indicates the time elapsed from the beginning of each music track.
  • some players have a facility to directly programme an arbitrary absolute time code so that the scanning spot of the light beam can be moved to any arbitrary position on the disc and any arbitrary music track can be played.
  • the number of tracks across which the scanning spot of the light beam must be displaced to reach the desired position is calculated from the absolute time code of the beginning of a desired music track and the absolute time code of the position from which a jump must be made.
  • the parameters of the relation between the number of tracks to be jumped and the absolute time code is dependent on the track pitch and the velocity with which the information has been recorded on the relevant disc. In accordance with the worldwide Compact Disc Standard this write velocity must be between 1.2 and 1.4 m/s and the track pitch must be between 1.5 and 1.7 ⁇ m.
  • the actual write velocity and track pitch of an arbitrary disc to be played are, however, not known.
  • the minimum write velocity and the maximum pitch are used as a basis for the calculation of the number of tracks to be jumped.
  • jumping to desired address is not very accurate so that in most cases a number of jumps must be made in order to reach the desired address.
  • the light beam may still be situated 800 to 1000 tracks before the track with the desired absolute time code.
  • the absolute time code on a CD-ROM disc is not only present in the sub-code signal but also at the start of each data block.
  • the various data blocks can now be read by searching the relevant absolute time code in the data.
  • the Philips CD-ROM player CM 100 incorporates a table stating the associated track number for each minute. The number of tracks to be jumped from a given address to the address of the data block to be read is determined by means of this table. In order to prevent overshoot of the desired position, the table stored in the player is based on the minimum write velocity and the maximum track pitch. This means that also in a CD-ROM player jumping to a desired position is not very accurate so that the searching time is relatively long.
  • control means comprise calculating means for calculating the parameters of said predetermined relation on the basis of the address codes obtained after a displacement of the scanning spot from a first position with a known address successively across a first and second known number of tracks.
  • the measures according to the invention provide the possibility of determining the parameters of the relation before the disc is played. Subsequently, the number of tracks which is to be jumped to reach a desired address code can be accurately calculated for the relevant disc. It has been found that one jump, short of approximately 10 tracks from the track with the desired address code is made by means of the apparatus according to the invention.
  • Fig. 1 is a block-schematic diagram of an apparatus according to the invention in which only the elements required to explain the operation of the invention are shown.
  • the apparatus comprises a motor 1 with which an optically readable disc 2 can be rotated.
  • the disc is, for example a digital audio disc on which digital audio information in the form of a spiral track of pits separated by intermediate areas is provided.
  • an optical system 3 which is provided with a laser 4 whose beam is focussed on the disc 2 by means of a lens system 5 which is shown diagrammatically.
  • the spot of the beam may be displaced radially across the disc 2 by radial displacement means 7 which may be, for example in the form of an arm which can be rotated about a shaft by means of a motor or a slide which can be displaced radially by means of a motor, whilst at least a portion of the optical system 3 is arranged on the arm or the slide.
  • the disc 2 is rotated about the shaft and the optical system 3 is moved in the radial direction in such a manner that the laser beam follows the information track with a constant linear velocity.
  • the laser beam is modulated by the information structure on the disc 2 and the beam reflected by the disc is applied via a semi-transparent mirror 6 to an optical detector 8 which converts the modulated light beam into a correspondingly modulated electric signal.
  • This signal is applied to a signal processing device 9 which derives the digital audio signal therefrom after demodulation and error correction, which signal is applied to output 10.
  • a plurality of control signals is also derived from the detector signal, which control signals are applied to a control device 11. These control signals are used, inter alia to cause the motor to rotate at the desired number of revolutions, to keep the beam focussed on the disc 2 and to control the radial displacement means in such a way that the beam continues to follow the information track accurately.
  • subcode information incorporating, inter alia the number, titles and composers of the music tracks and an absolute and a relative time code
  • the absolute time code is a code continuously extending along the track indicating the absolute time from the beginning of the track
  • the relative time code is a code indicating the absolute time from the beginning of a music track.
  • the absolute time codes of the beginning of the music tracks on the disc are indicated on the lead-in track of an audio disc. After starting the player these time codes are stored in a memory of the microprocessor 12. Since it must be possible to record a maximum number of 99 music tracks on a disc in accordance with the compact disc standard, only the minutes and seconds are indicated in the lead-in track. Since this does not provide the possibility of accurately finding the beginning of a music track, a jump to a position slightly beyond the beginning of a music track is first made by means of the absolute time code whereafter the beginning of a track is searched by means of the relative time code. In addition some commercially available compact disc players provide the facility of directly programming an absolute timecode in minutes, seconds and frames so that jumps can be made to any arbitrary position.
  • the beam is displaced by means of the radial displacement means 7 in the same manner on the basis of the absolute time code.
  • this number of tracks is dependent on the write velocity and the track pith of the relevant disc.
  • the compact disc audio standard prescribes that the write velocity should be 1.2 ⁇ v1 ⁇ 1.4 m/s and the track pitch should be 1.5 ⁇ s ⁇ 1.7 ⁇ m. These data are, however, unknown for an arbitrary disc to be played. To prevent overshoot far beyond the desired position or even beyond the lead-out track of the disc, the calculation of the number of tracks to be jumped is always based on the minimum write velocity and the maximum pitch. A number of jumps must therefore usually be made to reach the desired address.
  • the accuracy of jumping to a given position is increased by determining both the track pitch and the write velocity of a disc.
  • the three-point measurement can be performed after the disc is started and before a start is made with reading the actual audio information.
  • it is alternatively possible to jump from an arbitrary different position. For example, one can go first to the position with time code to 2 sec.
  • Each jump may be equal, for example, 5000 tracks, but they may also be unequal to one another.
  • the three-point measurement may not only be performed prior to reading, but also with the aid of jumps made during normal operation of the apparatus.
  • a number of jumps is usually required in the known apparatus so as to displace the light beam from a given address code to a desired address code.
  • the number of tracks to be jumped is then calculated from the known address code and the desired address code.
  • the address code reached is read and compared with the desired address code. If these codes differ considerably, a second jump is made, whilst the number of tracks to be jumped is calculated from the desired address code and the address code reached after the first jump. After the second jump the address code reached is read again. If necessary, more jumps are made to reach the desired address code.
  • the write velocity and the track pitch of the relevant disc can be calculated from the number of tracks of the first and the second jump and from the address codes prior to the first jump and after the first and the second jump.
  • Figure 2 shows the flow chart of the programme performed by the microprocessor 12 in the control means 11 to determine the write velocity V and the track pitch S of a disc.
  • a variable k is set at the value 1.
  • the programme can be performed once again after the track pitch S and the write velocity V have been calculated, with two jumps over a different number of tracks being made from the same starting position of the same number of tracks as with the first time being jumped from a different starting position.
  • the track pitch S and the write velocity V are again calculated from the data obtained, whereafter the arithmetical mean value of the two results is determined. It is of course alternatively possible to perform the programme more than twice.
  • the invention has been described with reference to an apparatus for playing digital audio discs in which the absolute time code is present in the sub-code information.
  • the apparatus of Figure 1 may, however, alternatively be suitable for playing digital data discs.
  • the absolute time code on such discs is not only present in the sub-code information but also in the actual data.
  • the absolute time code is used as an address to be able to read the different data blocks. Jumping to a given absolute time code in order to read a specific data block is, however, effected in the same manner as with an audio disc.
  • the apparatus according to the invention is suitable for reading any type of optically readable record carrier in which information provided with continuous address codes is recorded.

Claims (2)

  1. Gerät zur Wiedergabe von mit einer vorgegebenen Schreibgeschwindigkeit und einem vorgegebenen Spurabstand in nahezu konzentrischen Spuren auf einem optisch lesbaren Aufzeichnungsträger (2) aufgezeichneter Information, wobei die Information einen sich kontinuierlich entlang der Spur erstreckenden und die absolute Zeit vom Beginn der Spuren anzeigenden Adreßcode enthält, so daß eine vorbestimmte Beziehung zwischen dem Adreßcode und der Anzahl der Spuren, in radialer Richtung gezählt, besteht, wobei die erwähnte Beziehung von der Schreibgeschwindigkeit und dem Spurabstand abhängende Parameter hat, welches Gerät umfaßt:
    - eine optische Ausleseeinrichtung (3) zur Richtung eines Lichtbündels auf den Aufzeichnungsträger (2), wobei das Lichtbündel einen Abtastfleck auf dem Aufzeichnungsträger (2) erzeugt und das Lichtbündel durch die von dem Abtastfleck abgetastete Information moduliert wird;
    - eine Detektionseinrichtung (8) zur Lieferung eines entsprechend dem modulierten Lichtbündel modulierten Signals;
    - eine Signalverarbeitungseinrichtung (9) zur Herleitung eines Ausgangssignals und zur Herleitung von Adreßcodes aus dem Signal der Detektionseinrichtung;
    - Radialverschiebemittel (7) zur Verschiebung des Abtastfleckes in radialer Richtung über den Aufzeichnungsträger (2);
    Steuerungsmittel (11) mit
    - Mitteln zur Beestimmung (12) der Anzahl der aufder Grundlage der genannten vorbestimmten Beziehung zu passierenden Spuren für den Fall, daß der Abtastfleck von einer Starposition mit bekannter Adresse zu einer Position mit gewünschter Adresse bewegt werden soll, und mit Mitteln (12) die die Radialverschiebemittel steuern, um den Abtastfleck über die festgelegte Spurenzahl zu verschieben,
    dadurch gekennzeichnet, daß die Steuerungsmittel (12) Rechenmittel (14) enthalten zur Berechnung der Parameter der vorbestimmten Beziehung auf der Grundlage der nach Verschiebung des Abtastfleckes von einer ersten Position mit einer bekannten Adresse über nacheinander eine erste und eine zweite bekannte Spurenzahl erhaltenen Adreßcodes.
  2. Gerät nach Anspruch 1, dadurch gekennzeichnet, daß die Rechenmittel (14) auch geeignet sind, um die Parameter aufder Grundlage von Adreßcodes von nach Verschiebung des Abtastfleckes von einer zweiten Position mit einer bekannten Adresse über nacheinander eine dritte und eine vierte bekannte Spurenzahl erhaltenen Positionen zu berechnen, und daß die Rechenmittel auch geeignet sind, um den arithmetischen Wert der berechneten Parameterwerte zu berechnen.
EP88201730A 1987-08-17 1988-08-12 Gerät zur Wiedergabe eines optisch lesbaren Aufzeichnungsträgers Expired - Lifetime EP0307982B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL8701925 1987-08-17
NL8701925 1987-08-17

Publications (2)

Publication Number Publication Date
EP0307982A1 EP0307982A1 (de) 1989-03-22
EP0307982B1 true EP0307982B1 (de) 1992-11-04

Family

ID=19850461

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88201730A Expired - Lifetime EP0307982B1 (de) 1987-08-17 1988-08-12 Gerät zur Wiedergabe eines optisch lesbaren Aufzeichnungsträgers

Country Status (5)

Country Link
US (1) US5047999A (de)
EP (1) EP0307982B1 (de)
JP (1) JP2916502B2 (de)
KR (1) KR0130474B1 (de)
DE (1) DE3875686T2 (de)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3014798B2 (ja) * 1991-04-20 2000-02-28 株式会社リコー ヘッド移動制御方法および光ディスク装置
JP3110856B2 (ja) * 1992-04-22 2000-11-20 オリンパス光学工業株式会社 光学ヘッドアクセス制御装置
JPH07130149A (ja) * 1993-10-29 1995-05-19 Toshiba Corp 時間表示機能付き再生装置
JPH08167154A (ja) * 1994-12-08 1996-06-25 Pioneer Electron Corp ディスク再生装置
KR100228477B1 (ko) * 1995-09-30 1999-11-01 윤종용 멀티 세션 디스크 및 고속 억세스 방법
JPH09120548A (ja) * 1995-10-25 1997-05-06 Shinano Kenshi Co Ltd 光ピックアップの駆動装置
JPH117737A (ja) * 1997-06-17 1999-01-12 Funai Electric Co Ltd ディスク装置
CN1983416B (zh) * 2005-12-15 2011-01-26 广明光电股份有限公司 光盘数据轨距的判别方法
WO2007143693A2 (en) 2006-06-06 2007-12-13 Channel D Corporation System and method for displaying and editing digitally sampled audio data

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3662353A (en) * 1970-06-01 1972-05-09 Eg & G Inc Storing digital data on a recording disk with the data time base proportional to disk angular velocity
US4340949A (en) * 1980-07-31 1982-07-20 Rca Corporation Processor controlled video disc servo system
US4759007A (en) * 1981-12-10 1988-07-19 Discovision Associates Storage medium track pitch detector
JPS6050676A (ja) * 1983-08-31 1985-03-20 Toshiba Corp ディスクレコ−ド再生装置
US4578786A (en) * 1984-07-06 1986-03-25 Storage Technology Partners Ii Track pitch calibration system for use in optical storage devices
JPH0814943B2 (ja) * 1985-03-20 1996-02-14 松下電器産業株式会社 番地検索装置
JPH061611B2 (ja) * 1985-05-20 1994-01-05 株式会社日立製作所 情報記録デイスクのアクセス制御装置
JP2590813B2 (ja) * 1986-02-18 1997-03-12 ソニー株式会社 データの記録方法

Also Published As

Publication number Publication date
EP0307982A1 (de) 1989-03-22
JPS6489029A (en) 1989-04-03
US5047999A (en) 1991-09-10
DE3875686T2 (de) 1993-05-27
KR0130474B1 (ko) 1998-04-17
DE3875686D1 (de) 1992-12-10
KR890004313A (ko) 1989-04-21
JP2916502B2 (ja) 1999-07-05

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